For many years it has been known that sensitive and specific methods of determination can be developed for many substances based on an immunochemical reaction, i.e., a reaction between two or more immunocomponents, such as, for example, between an antigen and antibody.
An antigen is a substance that, if injected into an animal for which the antigen in question is foreign to the body, gives rise to the formation of an immunological defensive reaction, and an antibody is a protein molecule (an immunoglobulin) that is formed by the animal in whose blood it is present as a reaction to the penetration of the antigen, and which can enter into a specific bond with the antigen against which it is directed. Although this mechanism is in principle regarded as a defensive mechanism against harmful substances that penetrate a living organism (e.g., a virus infection), it can be used for the creation of antibodies against any arbitrary antigen. The degree of harmfulness of the antigen is of no relevance. The blood serum of such an animal, or fractions thereof containing antibodies, can be employed as a reagent for the antigen. A very large number of substances of different structure can function as antigens. Thus, in test animals antibodies are created by almost all sorts of protein molecules, against glycoproteins, against certain carbohydrates, lipids and, after the use of certain artifices, even against low-molecular substances such as steroid hormones and prosta-glandins.
This means that for all these classes of substance immunochemical methods of determination can be developed.
This invention relates to methods for determining antigens by means of an immunochemical reaction, whereby the antigen must enter into a bond with at least two antibody molecules, characterized in that two or more different sorts of monoclonal antibodies directed against the same antigen are used.